The overall goal of this HIVRAD Program is to develop a second generation HIV -1 vaccine based on recombinant adeno-associated virus (rAAV) vectors. The proposed research in this application builds on our experience with a first generation rAAV /HIV vaccine that is being readied for human trials. Although the first generation vaccine is a promising candidate, we believe that substantial room for improvement remains. Based on our preliminary data, we have developed a series of hypothesis driven experiments in Projects 1 -4 to achieve this goal. Two major themes will be developed. First, we will enhance antigen- specific T cell responses to the vaccine by (i) significantly augmenting vaccine gene delivery (Projects 1 and 2) and (ii) directly engaging and modifying host immune responses (Projects 1 and 3). Second, through a novel and innovative approach, we will generate serum antibodies that neutralize primary isolates of HIV -1 by using rAAV vectors to transfer human antibody genes of predetermined specificity to skeletal muscle (project 4). The convergence of these themes will form the basis of the second-generation rAAV /HIV vaccine. Two important and intended by-products of this Program will be: (i) a better understanding of how gene-based vaccines actually work (Project 3); and, (b) improved vectors for general gene delivery to muscle (Project 2). The entire Program will be supported by four Cores. Core A is the Administrative Office, and as such will coordinate the Program and ensure the timely execution of the proposed research. Core B will serve as the central testing facility for non-human primates. Core C is the non-human primate immunology core and is directly affiliated with Core B. Core D supports viral vector production for the Program.